1999 FORD EXPLORER 4.0 NO SPARK

[JOHN07]

I HAVE A 99 EXPLORER 4.0 THAT JUST DIED AT A STOP LIGHT. THOUGHT IT WAS THE FUEL PUMP THE WAY IT DIED, SO I REPLACED IT BUT IT TURNS OUT I HAVE NO POWER GOING TO MY IGNITION COIL. IVE REPLACED ALL THE FUSES, RELAYS, CRANK SENSOR AND THE PIGTAIL FOR THE SENSOR, IVE CHECKED MY INERTIA SWITCH AS WELL AND ITS NOT TRIPPED. MY CHECK ENGINE LIGHT COMES ON THEN GOES OUT WHEN CRANKING, MY ANTI-THEFT LIGHT BLINKS SLOWLY, BUT NOTHING ELSE OUT OF THE NORM. AT MY WHITS END ANY ADVICE ON WHAT MY NEXT STEP IN TROUBLE SHOOTING WOULD BE MINUS THE PCM?

 

[410Fortune]

crankshaft position sensor on the front of the engine is known for going out and causing a no spark condition

Is your 99 a SOHC engine or OHV 4.0?

 

[JOHN07]

crankshaft position sensor on the front of the engine is known for going out and causing a no spark condition

Is your 99 a SOHC engine or OHV 4.0?

IVE ALREADY REPLACED THE CRANKSHAFT POSITION SENSOR, AND THE PIGTAIL THAT GOES TO IT. THE ENGINE IS AN OHV.

 

[koda2000]

Spark is controlled by the crank position sensor. If you replaced the sensor and its pig tail and still are not getting spark the sensor signal sounds like it's not getting to the PCM or the PCM signal to fire the ignition coil is not getting to the coil. You will need to figure out which is the case. Could be an electrical connection issue, a wiring issue or perhaps the PCM itself (which IMO is the least likely).

 

[Turdle]

Try this, you might just have a loose plug.

2nd gen issues? Try this first!

Does check engine light come on when the key is turned on, does it flash while cranking?

 

[JOHN07]

Try this, you might just have a loose plug.

2nd gen issues? Try this first!

Does check engine light come on when the key is turned on, does it flash while cranking?

THE CHECK ENGINE LIGHT DOES COME ON WHEN THE KEY IS ON, BUT WHILE CRANKING IT GOES OUT.

 

[410Fortune]

Do you have power at the red wire at injectors with key in the on position?
How do you know there is no spark?
theft light is blinking, could it just be pats disabling your injectors......

 

[JOHN07]

Do you have power at the red wire at injectors with key in the on position?
How do you know there is no spark?
theft light is blinking, could it just be pats disabling your injectors......

with the key on there is no power to the red wire that plugs into the coil pack. at first I pulled a plug wire off and checked for spark, once I determined there was no spark I back tracked to the pigtail, and nothing is there.

 

[koda2000]

with the key on there is no power to the red wire that plugs into the coil pack. at first I pulled a plug wire off and checked for spark, once I determined there was no spark I back tracked to the pigtail, and nothing is there.

I don't know that you should expect to see voltage (or much voltage) at the crank position sensor. If I recall correctly both wires that are connected to the CPS are black, which would lead me to think that the CPS (a hall-effect type of sensor) is a ground which is opened or closed as the tone ring on the crankshaft passes by it. I do recall I tested my CPS using a magnet and my VOM, which showed continuity when I touched the magnet to the sensor's business end. My issue was wiring related.

Have you tried unplugging/disconnecting and re-seating your PCM and engine harness connectors as @Turdle suggested? Wiring and connections on a 20 year old vehicle can get flaky as they get corroded and/or brittle with age. Also, mice and squirrels love to chew on wiring for some reason.

 

[JOHN07]

I don't know that you should expect to see voltage (or much voltage) at the crank position sensor. If I recall correctly both wires that are connected to the CPS are black, which would lead me to think that the CPS (a hall-effect type of sensor) is a ground which is opened or closed as the tone ring on the crankshaft passes by it. I do recall I tested my CPS using a magnet and my VOM, which showed continuity when I touched the magnet to the sensor's business end. My issue was wiring related.

Have you tried unplugging/disconnecting and re-seating your PCM and engine harness connectors as @Turdle suggested? Wiring and connections on a 20 year old vehicle can get flaky as they get corroded and/or brittle with age. Also, mice and squirrels love to chew on wiring for some reason.

no I haven't tried the pcm connection yet, I figured id try that on my lunch, since the vehicle is at my work place.

 

[410Fortune]

Do you have power with the key on at the red wire at the injector(s)? How about at the MAS?
this red wire is power distribution from the PCM
if no power is present with the key on then you need to check fuses and relays over very closely

Dont forget Rabbits!!! Rabbits love to eat under hood wiring. My old neighbor used to prop his hood up everyday because it was the only way to keep the rabbits out from under his hood

 

[JOHN07]

Do you have power with the key on at the red wire at the injector(s)? How about at the MAS?
this red wire is power distribution from the PCM
if no power is present with the key on then you need to check fuses and relays over very closely

Dont forget Rabbits!!! Rabbits love to eat under hood wiring. My old neighbor used to prop his hood up everyday because it was the only way to keep the rabbits out from under his hood

well I did all of my tests still had no power to the ignition coil, nor to the mas, so I hooked up one of my coworkers snap on scan tools and it would not read the pcm, so I presume that's the problem.

 

[410Fortune]

Check for power going to the PCM
And also PCM power when you turn the key on there are 12V+ constant, and 12V ACC power feeds to PCM

suspect PCM / EEC fuse and or EEC relay

 

[JOHN07]

ok so I finally got around to checking the pcm harness and I only have power to pin 55 with key on nothing else. should there be power else where on that harness? or could it just be that the pcm is shot

 

[Turdle]

Check engine light will not come on if the PCM is not powered up, so, I am confused. You said earlier it did, and went out while cranking.

 

[JOHN07]

Check engine light will not come on if the PCM is not powered up, so, I am confused. You said earlier it did, and went out while cranking.

the check engine light does come on, when the key is on and when you crank it goes out. I down loaded a diagram of the pcm connector and pin 55 shows its keep power alive b+ so im not sure if that's constant power to the pcm, or if there is suppose to be power at some other wire for the pcm to read properly since my scan tool isn't reading the pcm

 

[974X4BLACKSPORT]

Start be putting a scanner on it and for any codes, or security issues.

 

[JOHN07]

Start be putting a scanner on it and for any codes, or security issues.

when I put the scanner on initially there was a bunch of codes, but I think they were old codes. they were mainly for the air bag, door ajar, low battery and a few other ones, but none of them pertained to the functionality of the engine. I have a 99 f150 that was doing the same thing as my explorer, and I just ended up replacing the pcm, but that didn't fix the problem, so I pretty much just wasted a few hundred dollars, if I can get this problem figured out maybe itll be the same problem as my truck. I just don't want to replace the pcm and that not be the issue.

 

[Turdle]

If you read codes the PCM is not dead. However somewhere an output could be shorted to ground due to a bad sensor or wiring. Let's put that on the back shelf for now.


All of your fuses are good?
You never posted that you took the center bolts out of the 2 main PCM connectors ( thread I linked above) and checked the connectors over. I assume you did that?

 

[JOHN07]

If you read codes the PCM is not dead. However somewhere an output could be shorted to ground due to a bad sensor or wiring. Let's put that on the back shelf for now.


All of your fuses are good?
You never posted that you took the center bolts out of the 2 main PCM connectors ( thread I linked above) and checked the connectors over. I assume you did that?

yes I took both of the connectors off, cleaned them put some dielectric grease on them and put them back on, and made sure they were tight, I tested all of the fuses, they were all good, but I just went ahead and replaced all of the fuses and relays, just to eliminate that possible issue.